President Trump turned the power of the White House against the news media on Friday, escalating his attacks on journalists as “the enemy of the people” and berating members of his own F.B.I. as “leakers” who he said were putting the nation at risk.

.. And in a series of Twitter posts, he assailed the F.B.I. as a dangerously porous agency, condemning unauthorized revelations of classified information from within its ranks and calling for an immediate hunt for leakers.

Hours after the speech, as if to demonstrate Mr. Trump’s determination to punish reporters whose coverage he dislikes, Sean Spicer, the White House press secretary, barred journalists from The New York Times and several other news organizations from attending his daily briefing, a highly unusual breach of relations between the White House and its press corps.

.. Mr. Trump and members of his inner circle are eager to use the prerogatives of the presidency to undercut those who scrutinize him, dismissing negative stories as lies and confining press access at the White House to a few chosen news organizations considered friendly.

.. “The fake news doesn’t tell the truth,” Mr. Trump said to the delight of the conservatives packed into the main ballroom at the Gaylord National Resort and Convention Center just south of Washington. “It doesn’t represent the people, it doesn’t and never will represent the people, and we’re going to do something about it.”

.. Breitbart News, the One America News Network and The Washington Times, all with conservative leanings. Journalists from ABC, CBS, The Wall Street Journal, Bloomberg and Fox News also attended.

.. Mr. Trump, in his attack on the news media at the conservative gathering, complained at length about the use of anonymous sources in news stories, charging that some reporters were fabricating unnamed sources to level unfair charges against him.

“They shouldn’t be allowed to use sources unless they use somebody’s name,” Mr. Trump said. “Let their name be put out there.”

.. Those comments came shortly after his own aides had held a briefing for the White House press pool on the condition of anonymity to deny CNN’s story suggesting there had been improper contact between the White House and the F.B.I. regarding the Times article on Russian contacts.